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Explainer: how is it that people can recover from serious brain injury?

US Senator Gabrielle Giffords was shot in the head but is said to be recovering well. AAP

The human brain is often referred to as the most complex organ on the planet. It is responsible for an incalculable number of tasks, thoughts and functions every second of everyday of our lives.

The brain controls our emotions, our perceptions and our memories. In short, it is what makes us who we are.

Within the human brain, there are up to one hundred billion nerve cells, each with countless connections to each other. This complexity of connectivity is responsible for the limitless imagination and creativity of the human race.

This same complexity is also the reason for deficits in memory and function following disease and traumatic brain injury, such as those resulting from car accidents or gunshot wounds.

Understanding the brain

Traditionally, the brain was thought to be a static organ incapable of regeneration after the completion of embryonic development.

But in the past few decades, there’s been a radical shift away from this belief: we now know the adult brain is a very “plastic” organ, capable of forming new nerve connections.

It even maintains the ability to continually produce new neurons or nerve cells throughout life.

So where do these new neurons come from? Most readers have undoubtedly heard of stem cells. Unfortunately, most public attention has focused on the controversial use and study of embryonic stem cells.

During development, embryonic stem cells give rise to all our organs, including the brain.

Stem cells’ ability to turn into cells with specific roles in the body comes at the cost of the developing embryo and provides the basis for moral and ethical objections.

Much less media attention is given to the remarkable fact that the majority of organs in the adult body retain a small population stem cells specific only to that organ.

In an adult body, these cells continually replenish and replace cells lost during the normal course of living.

It has recently been discovered that the adult brain also contains a population of this kind of stem cell: researchers have identified the presence of neural stem cells in animal brains.

Not only have we shown that these cells are present in adult animals, we have also identified this type of cell in animals of very advanced age.

More importantly, we have demonstrated that it’s possible to activate these cells and produce new neurons after brain injury.

We are now trying to understand how these stem cells are activated – what are the mechanisms that trigger new nerve cell formation?

Answering this question will open up the possibility of developing new treatment strategies for all manner of neurodegenerative diseases, including but not limited to dementia, Huntington’s disease and depression.

Post-trauma brain regeneration

Studies also show different regions of the brain possess differing capabilities to respond to disease and injury.

This adds even more complexity to the process of regeneration and partly explains why some people recover from a traumatic brain injury while others do not.

First, the likelihood of recovery is influenced by the injury itself – in instances such as U.S. Senator Gabrielle Giffords’ gunshot wound, there’s massive damage to the brain tissue.

Another set of factors contribute to the severity of the trauma in the aftermath of the injury. These include increases in cranial pressure and disruption to the blood flow within the brain.

Improvements in diagnostic techniques including CT scans and magnetic resonance imaging (MRI) now allow for efficient and accurate investigation of the injured brain region.

This helps clinicians offer better treatment to patients in the initial stages following injury.

Rehabilitation treatment is also quite advanced with scientists showing physical therapy and exercise stimulate the formation of new neurons and aid in the regeneration of the brain.

While traumatic brain injuries have to be considered on a case-by-case basis the potential for regeneration within the adult brain is a reality.

There are no drugs approved for improving recovery outcome following traumatic brain injury at present but scientists are investigating the mechanisms involved in regeneration in the hope of changing this.

We have come a long way from the original picture of an organ we thought incapable of producing new neurons.

The brain is a truly remarkable organ that continues to replace cells throughout life and has the ability to regenerate following traumatic injury and disease.

The challenges it poses are exceptionally complex but not insurmountable.

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